delay for delay. Delay for delay is to sell a debt against one man for a debt against another man."

Malik said, "If someone advances for goods to be delivered after a time, and those goods are neither something to be eaten nor drunk, he can sell them to whomever he likes for cash or goods, before he takes delivery of them, to some one other than the person from whom he purchased them. He must not sell them to the person from whom he bought them except in exchange for goods which he takes possession of immediately and does not defer."

Malik said, "If the delivery date for the goods has not arrived, there is no harm in selling them to the original owner for goods which are clearly different and which he takes immediate possession of and does not defer."

Malik spoke about the case of a man who advanced dinars or dirhams for four specified pieces of cloth to be delivered before a specified time and when the term fell due, he demanded delivery from the seller and the seller did not have them. He found that the seller had cloth but inferior quality, and the seller said that he would give him eight of those cloths. Malik said, "There is no harm in that if he takes the cloths which he offers him before they separate. It is not good if delayed terms enter into the transaction. It is also not good if that is before the end of the term, unless he sells him cloth which is notthetypeof cloth for which he made an advance.
Muwatta Malik Book 31, Hadith 70